OpenSSF/OSV advisory MAL-2026-4481 confirms this npm version as malicious. On `npm install`, the package's postinstall hook runs `id` to capture the installer's uid/gid/group identity and opens a raw TCP socket to host.docker.internal:9999, writing the command output to that listener. The package's declared main (index.js) is a two-line stub exporting `{}` — there is no library functionality, the postinstall beacon is the package's sole purpose. host.docker.internal resolves to the Docker...
Source
OpenSSF Malicious Packages via OSV
Summary
Malicious code in arc-diag-util (npm)
Details
On `npm install`, the package's postinstall hook runs `id` to capture the installer's uid/gid/group identity and opens a raw TCP socket to host.docker.internal:9999, writing the command output to that listener. The package's declared main (index.js) is a two-line stub exporting `{}` — there is no library functionality, the postinstall beacon is the package's sole purpose. host.docker.internal resolves to the Docker host from inside a container, so the pattern is specifically designed to escape sandboxed CI/build containers and report installer identity to a listener on the build host. The hollow library body combined with a generic 'diagnostic utility' name is consistent with a dependency-confusion attempt against an internal package name.
Decision reason
OpenSSF Malicious Packages via OSV confirms arc-diag-util@1.0.1 as malicious (MAL-2026-4481): Malicious code in arc-diag-util (npm)